a) l and m are the maximal elements as they have no successor
b) a, b and c are the minimal elements as they have no predecessor
c) There is no greatest elements as the 2 maximal elements are incomparable
d) Same as above, a, b and c are minimal and incomparable
e) Upper bounds : a={a,d,i,j,l,h,k,m} b={b,e,h,k,m,d,i,j,l} c={c,f,g,k,m,l} (a,b,c)={k,m,l}
f) Least upper bound of {a,b,c} is k
g) Lower bounds : f={f,c} g={g,f,c} h={h,e,b,d,a}
h) Greatest lower bound of {f,g,h} does not exist as they have no lower bounds in common